如何使用 java 中的线程创建多个坠落对象？

Question

** Here i created only one moving object,i want to create more objects which falls down and has random X coordinate.i know i should implement runnable and i should create squres then store them in a collection but its really hard for me to merge everything.i also might have done some mistakes btw. Could you help me some? **

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Random;

public class Project3 extends JFrame {
    public Project3(){
        super("Game");
        setSize(600,600);
        add(new Game(600,600));
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setVisible(true);

    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new Project3());
    }

    class Squares{
        public int x;
        public int y;

        public Squares(int x, int y) {
            this.x = x;
            this.y = y;
        }

        public int getX() {
            return x;
        }

        public void setX(int x) {
            this.x = x;
        }

        public int getY() {
            return y;
        }

        public void setY(int y) {
            this.y = y;
        }
    }

    class Game extends JPanel implements ActionListener {
        private int score;
        private java.util.List<Squares> shapeList=new ArrayList<>();
        private boolean play ;
        private int X=50;
        private int Y=0;
        Timer timer=new Timer(10,this);

        public Game(int w , int h){
            Dimension d = new Dimension(w, h);
            setBackground(Color.BLUE);

        }

        @Override
        public void paint(Graphics g) {
            super.paint(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.fillRect(X,Y,60,60);
            timer.start();

        }

        @Override
        public void actionPerformed(ActionEvent e) {
            Y=Y+5;
            repaint();
            if(Y==600){
                Random random=new Random();
                Y=0;
                X=random.nextInt(600-60);
            }
        }
    }
}

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;

public class Project3 extends JFrame {
    public Project3() {
        super("Game");
        setSize(600, 600);
        add(new Game(600,600));
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new Project3());
    }

    class Square {
        public int squareX;
        public int squareY;
        int squareW = 25;
        int squareH = 25;

        public Square(int X, int Y) {
            this.squareX = X;
            this.squareY = Y;
        }

        public int getSquareX() {
            return squareX;
        }

        public void setSquareX(int X) {
            this.squareX = X;
        }

        public int getSquareY() {
            return squareY;
        }

        public void setSquareY(int Y) {
            this.squareY = Y;
        }

    }


    class Game extends JPanel implements ActionListener ,Runnable,MouseListener {
        public int score;
        private java.util.List<Square> shapeList = new ArrayList<>();
        Timer timer = new Timer(10, this);
        private boolean play= true;

        public Game(int w, int h) {
            Dimension d = new Dimension(600, 600);
            setBackground(Color.BLUE);
            add(new Label("SCORE...."),BorderLayout.PAGE_END);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.setColor(Color.YELLOW);
            for (Square s:shapeList) {
                g.fillRect(s.squareX,s.squareY,25,25);
            }
        }


        @Override
        public void actionPerformed(ActionEvent e) {
            for (Square k : shapeList) {
                k.setSquareY(k.getSquareY() + 5);
                repaint();
            }
        }
        public void stop() {
            play = false;
        }
        @Override
        public void run() {
            while(play){

                int randomNumber=(int)(Math.random()*600)+1;
                shapeList.add(new Square(randomNumber,0));

                for (Square k : shapeList) {
                    if (k.getSquareY()== 600) {
                    stop();
                }try {
                    Thread.sleep(500);
                } catch (InterruptedException ignored) {
                    }
            }
        }
    }

        @Override
        public void mouseClicked(MouseEvent e) {

        }

        @Override
        public void mousePressed(MouseEvent e) {
            int mouseX=e.getX();
            int mouseY=e.getY();
            for (Square s:shapeList){
                if ((mouseX > s.squareX) && (mouseX < s.squareX + s.squareW) && (mouseY > s.squareY) && (mouseY < s.squareY + s.squareH)) {
                    shapeList.remove(s);
                    score++;
                }
            }

        }

        @Override
        public void mouseReleased(MouseEvent e) {

        }

        @Override
        public void mouseEntered(MouseEvent e) {

        }

        @Override
        public void mouseExited(MouseEvent e) {

        }
    }
}

Answer 1

This code produces three layers of 'snow flakes' which drift towards the bottom of the screen.

Have a look over it, for tips:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.util.Random;

public class AnimatedSnowFall {

    private JComponent ui = null;

    AnimatedSnowFall() {
        initUI();
    }

    public final void initUI() {
        if (ui != null) {
            return;
        }

        ui = new JPanel(new BorderLayout(4, 4));
        ui.setBorder(new EmptyBorder(4, 4, 4, 4));

        ui.add(new SnowFall());
    }

    public JComponent getUI() {
        return ui;
    }

    public static void main(String[] args) {
        Runnable r = () -> {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (Exception useDefault) {
            }
            AnimatedSnowFall o = new AnimatedSnowFall();

            JFrame f = new JFrame(o.getClass().getSimpleName());
            f.setResizable(false);
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setLocationByPlatform(true);

            f.setContentPane(o.getUI());
            f.pack();
            f.setMinimumSize(f.getSize());

            f.setVisible(true);
        };
        SwingUtilities.invokeLater(r);
    }
}

class SnowFall extends JPanel implements ActionListener {

    Dimension prefSize = new Dimension(1600, 900);
    SnowFlake[] farFlakes = new SnowFlake[200];
    SnowFlake[] midFlakes = new SnowFlake[150];
    SnowFlake[] closeFlakes = new SnowFlake[75];
    Color farColor = new Color(100,100,255);
    Color midColor = new Color(150,150,255);
    Color closeColor = new Color(255,255,255);

    SnowFall() {
        setBackground(Color.BLACK);
        for (int ii = 0; ii < farFlakes.length; ii++) {
            farFlakes[ii] = new SnowFlake(prefSize.width, prefSize.height, 2, 4);
        }
        for (int ii = 0; ii < midFlakes.length; ii++) {
            midFlakes[ii] = new SnowFlake(prefSize.width, prefSize.height, 3, 6);
        }
        for (int ii = 0; ii < closeFlakes.length; ii++) {
            closeFlakes[ii] = new SnowFlake(prefSize.width, prefSize.height, 4, 8);
        }
        Timer timer = new Timer(50, this);
        timer.start();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        g.setColor(farColor);
        for (SnowFlake snowFlake : farFlakes) {
            snowFlake.draw(g);
        }

        g.setColor(midColor);
        for (SnowFlake snowFlake : midFlakes) {
            snowFlake.draw(g);
        }

        g.setColor(closeColor);
        for (SnowFlake snowFlake : closeFlakes) {
            snowFlake.draw(g);
        }
    }

    @Override
    public Dimension getPreferredSize() {
        return prefSize;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        repaint();
    }
}

class SnowFlake {

    int w;
    int h;
    int x;
    int y;
    int size;
    int speed;
    static Random r = new Random();

    SnowFlake(int w, int h, int size, int speed) {
        this.w = w;
        this.h = h;
        x = r.nextInt(w);
        y = r.nextInt(h);
        this.size = size;
        this.speed = speed;
    }

    public void draw(Graphics g) {
        y += speed;
        if (y > h) {
            x = r.nextInt(w);
            y = 0;
        }
        g.fillOval(x, y, size, size);
    }
}